1. Field of the Invention
The present invention relates to an apparatus and method for inspecting a liquid crystal display.
2. Discussion of the Related Art
As the information-oriented society has arrived, a requirement for flat panel displays that are light and thin and have lower power consumption is on the rise.
Among the flat panel displays, liquid crystal displays have been widely used for laptop computers and desktop computers.
Generally, a liquid crystal display includes two substrates facing each other, electric field generating electrodes formed on inner surfaces of the substrates, and a liquid crystal material injected in a space defined between the substrates. When a voltage is applied to the electrodes, liquid crystal molecules are twisted by an electric field to vary transmittance of the light, by which an image is displayed.
In the related art, many inspection processes are performed in the course of manufacturing the liquid crystal display. Particularly, after an array substrate is made, an array test process is performed to check for a pixel defect and a line cut, and the like. After the array substrate is attached to a color filter substrate, a lightening test for the liquid crystal panel is performed in a cell process.
In the cell process, an auto-probe device is used to allow a proof pin to contact the liquid crystal panel, after which a tester checks for the defect of the liquid crystal panel through a test using an optical device and his/her eyes in a state where the liquid crystal panel is driven.
That is, after the test signal is applied to the liquid crystal panel in the auto-probe device, a light source of a backlight is variously turned on to inspect a point defect and a line defect of the liquid crystal panel.
However, the test method of the related art has the following limitations.
First, as the liquid crystal display is enlarged above 40 inches, the test using the tester's eyes has a limitation.
Second, since the point and line defects of the liquid crystal panel are performed by the tester, after selecting defect candidates in advance, determining pass or fail by precisely inspecting the liquid crystal panel, it takes long time to perform the test.
Third, for the point defect, it is difficult to discriminate between a foreign substance on an outer surface of the liquid crystal panel or a polarizing panel and a foreign substance on an inner surface of the liquid crystal panel.
Particularly, the point defect caused by the foreign substance on the inner surface of the liquid crystal panel is a real defect that is directly related to the defect of the liquid crystal panel. Therefore, an accurate inspection for the point defect is required. However, the inspection method of the related art cannot perform the accurate inspection.